拼写输入短词居中长词可滚动

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

LearnEnglish/LearnEnglish/Views/SpellingInputView.swift

@@ -5,6 +5,7 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
 
     private let hiddenField = UITextField()
     private let stack = UIStackView()
+    private let scrollView = UIScrollView()
 
     private var chars: [String] = []
     private var blankPositions: [Int] = []
@@ -21,7 +22,6 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
     override init(frame: CGRect) {
         super.init(frame: frame)
 
-        let scrollView = UIScrollView()
         scrollView.showsHorizontalScrollIndicator = false
         scrollView.showsVerticalScrollIndicator = false
         addSubview(scrollView)
@@ -158,6 +158,22 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
             return box
         }
         refreshBoxes()
+        DispatchQueue.main.async { [weak self] in
+            self?.updateAlignment()
+        }
+    }
+
+    private func updateAlignment() {
+        let totalWidth = CGFloat(chars.count) * 32 + CGFloat(max(chars.count - 1, 0)) * 6
+        let available = scrollView.bounds.width
+        if totalWidth <= available {
+            let inset = max(0, (available - totalWidth) / 2)
+            scrollView.contentInset = UIEdgeInsets(top: 0, left: inset, bottom: 0, right: inset)
+            scrollView.isScrollEnabled = false
+        } else {
+            scrollView.contentInset = .zero
+            scrollView.isScrollEnabled = true
+        }
     }
 
     @objc private func boxTapped(_ gesture: UITapGestureRecognizer) {